1. Field of the Invention
The present invention relates to a method and an apparatus for controlling a line pressure of an automatic transmission.
2. Description of the Related Art
A typical shift control apparatus of an automatic transmission controls hydraulic pressure of solenoid valves depending on inputs such as vehicle speed and throttle valve opening.
The automatic transmission includes a number of frictional elements. To shift, an off-going element is released, and an on-coming element is engaged. The operation of the off-going and on-coming elements is controlled by hydraulic pressure supplied thereto.
Typically, full line pressure is formed, and then the full line pressure is maintained until a final target shift-speed is engaged. Such a scheme may result in excessive pressure supply to the off-going element, delaying the release of the hydraulic pressure from the off-going element.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.